This picture is
taken from the German edition of the National Geographic (April 2000, p. 202).

Following
explanation is given:

This photo shows
the arrival of canaries from St. Andreasberg (Hartz Mountains) at a harbour
somewhere in the USA in 1928. The cages are made of wood. They are called "Vuchelheisle".
That's the slang of the miners of the Hartz Mountain area and means "bird
house". There were only males in that cages. In
the year 1883 C. Reiche from Alfeld shipped about 120000 male Hartz Mountain
Rollers to New York.